• Journal of Intelligence and Information Systems
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• v.17 no.4
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• pp.213-226
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• 2011

In global supply chain, the scheduling problems of large products such as ships, airplanes, space shuttles, assembled constructions, and/or automobiles are complicated by nature. New scheduling systems are often developed in order to reduce inherent computational complexity. As a result, a problem can be decomposed into small sub-problems, problems that contain independently small scheduling systems integrating into the initial problem. As one of the authors experienced, DAS (Daewoo Shipbuilding Scheduling System) has adopted a two-layered hierarchical architecture. In the hierarchical architecture, individual scheduling systems composed of a high-level dock scheduler, DAS-ERECT and low-level assembly plant schedulers, DAS-PBS, DAS-3DS, DAS-NPS, and DAS-A7 try to search the best schedules under their own constraints. Moreover, the steep growth of communication technology and logistics enables it to introduce distributed multi-nation production plants by which different parts are produced by designated plants. Therefore vertical and lateral coordination among decomposed scheduling systems is necessary. No standard coordination mechanism of multiple scheduling systems exists, even though there are various scheduling systems existing in the area of scheduling research. Previous research regarding the coordination mechanism has mainly focused on external conversation without capacity model. Prior research has heavily focuses on agent-based coordination in the area of agent research. Yet, no scheduling domain has been developed. Previous research regarding the agent-based scheduling has paid its ample attention to internal coordination of scheduling process, a process that has not been efficient. In this study, we suggest a general framework for agent-based coordination of multiple scheduling systems in global supply chain. The purpose of this study was to design a standard coordination mechanism. To do so, we first define an individual scheduling agent responsible for their own plants and a meta-level coordination agent involved with each individual scheduling agent. We then suggest variables and values describing the individual scheduling agent and meta-level coordination agent. These variables and values are represented by Backus-Naur Form. Second, we suggest scheduling agent communication protocols for each scheduling agent topology classified into the system architectures, existence or nonexistence of coordinator, and directions of coordination. If there was a coordinating agent, an individual scheduling agent could communicate with another individual agent indirectly through the coordinator. On the other hand, if there was not any coordinating agent existing, an individual scheduling agent should communicate with another individual agent directly. To apply agent communication language specifically to the scheduling coordination domain, we had to additionally define an inner language, a language that suitably expresses scheduling coordination. A scheduling agent communication language is devised for the communication among agents independent of domain. We adopt three message layers which are ACL layer, scheduling coordination layer, and industry-specific layer. The ACL layer is a domain independent outer language layer. The scheduling coordination layer has terms necessary for scheduling coordination. The industry-specific layer expresses the industry specification. Third, in order to improve the efficiency of communication among scheduling agents and avoid possible infinite loops, we suggest a look-ahead load balancing model which supports to monitor participating agents and to analyze the status of the agents. To build the look-ahead load balancing model, the status of participating agents should be monitored. Most of all, the amount of sharing information should be considered. If complete information is collected, updating and maintenance cost of sharing information will be increasing although the frequency of communication will be decreasing. Therefore the level of detail and updating period of sharing information should be decided contingently. By means of this standard coordination mechanism, we can easily model coordination processes of multiple scheduling systems into supply chain. Finally, we apply this mechanism to shipbuilding domain and develop a prototype system which consists of a dock-scheduling agent, four assembly- plant-scheduling agents, and a meta-level coordination agent. A series of experiments using the real world data are used to empirically examine this mechanism. The results of this study show that the effect of agent-based platform on coordinated scheduling is evident in terms of the number of tardy jobs, tardiness, and makespan.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.31-31
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• 2010

The growth of the high-quality GaN epilayers is of significant technological importance because of their commercializedoptoelectronic applications as high-brightness light-emitting diodes (LEDs) and laser diodes (LDs) in the visible and ultraviolet spectral range. The GaN-based heterostructural epilayers have the polar c-axis of the hexagonal structure perpendicular to the interfaces of the active layers. The Ga and N atoms in the c-GaN are alternatively stacked along the polar [0001] crystallographic direction, which leads to spontaneous polarization. In addition, in the InGaN/GaN MQWs, the stress applied along the same axis contributes topiezoelectric polarization, and thus the total polarization is determined as the sum of spontaneous and piezoelectric polarizations. The total polarization in the c-GaN heterolayers, which can generate internal fields and spatial separation of the electron and hole wave functions and consequently a decrease of efficiency and peak shift. One of the possible solutions to eliminate these undesirable effects is to grow GaN-based epilayers in nonpolar orientations. The polarization effects in the GaN are eliminated by growing the films along the nonpolar [$11\bar{2}0$] ($\alpha$-GaN) or [$1\bar{1}00$] (m-GaN) orientation. Although the use of the nonpolar epilayers in wurtzite structure clearly removes the polarization matters, however, it induces another problem related to the formation of a high density of planar defects. The large lattice mismatch between sapphiresubstrates and GaN layers leads to a high density of defects (dislocations and stacking faults). The dominant defects observed in the GaN epilayers with wurtzite structure are one-dimensional (1D) dislocations and two-dimensional (2D) stacking faults. In particular, the 1D threading dislocations in the c-GaN are generated from the film/substrate interface due to their large lattice and thermal coefficient mismatch. However, because the c-GaN epilayers were grown along the normal direction to the basal slip planes, the generation of basal stacking faults (BSFs) is localized on the c-plane and the generated BSFs did not propagate into the surface during the growth. Thus, the primary defects in the c-GaN epilayers are 1D threading dislocations. Occasionally, the particular planar defects such as prismatic stacking faults (PSFs) and inversion domain boundaries are observed. However, since the basal slip planes in the $\alpha$-GaN are parallel to the growth direction unlike c-GaN, the BSFs with lower formation energy can be easily formed along the growth direction, where the BSFs propagate straightly into the surface. Consequently, the lattice mismatch between film and substrate in $\alpha$-GaN epilayers is mainly relaxed through the formation of BSFs. These 2D planar defects are placed along only one direction in the cross-sectional view. Thus, the nonpolar $\alpha$-GaN films have different atomic arrangements along the two orthogonal directions ($[0001]_{GaN}$ and $[\bar{1}100]_{GaN}$ axes) on the $\alpha$-plane, which are expected to induce anisotropic biaxial strain. In this study, the anisotropic strain relaxation behaviors in the nonpolar $\alpha$-GaN epilayers grown on ($1\bar{1}02$) r-plane sapphire substrates by metalorganic chemical vapor deposition (MOCVO) were investigated, and the formation mechanism of the abnormal zigzag shape PSFs was discussed using high-resolution transmission electron microscope (HRTEM).

• Sleep Medicine and Psychophysiology
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• v.10 no.1
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• pp.39-51
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• 2003

Objectives: The Profile of Mood States (POMS) has been used broadly and frequently in various medical studies with various subjects. For the development and application of the Korean edition of POMS, called K-POMS, we translated POMS into Korean and then evaluated the reliability and validity of K-POMS. Methods: The subjects were 161 male students with a mean age of 18.1 years (15-30) and 244 female students with a mean age of 16.6 years (14-23). They were requested to perform K-POMS and SCL-90-R (Korean version) at the same time. Means, reliability coefficients, and test-retest correlations of K-POMS were calculated. Content validities, correlations with SCL-90-R, and discrimination validities in comparison with 76 depressive patients were obtained, and factor analyses were carried out. Results: Mean scores of Total Mood Disturbance (TMD) and some subscales (T, F, C, V factor) showed a significant difference between male and female students. The internal consistency coefficient ($\alpha$) of the total 65 items was 0.93, and ranged from 0.67 to 0.90 for subscales. Test-retest correlations of 43 subjects ranged from 0.27 to 0.63. Seven psychiatrists rated the properness of the content of each item as more than moderate degree (mean scale points=2.66, in the range of 0 to 4). Every subscale of KPOMS exhibited significant correlation with the matching subscale of SCL-90-R. Mean scores of K-POMS of the total 405 subjects were significantly different from those of the 76 depressive subjects after age correction. Six factors were extracted, accounting for 51.2% of total variance. Factor 6 consisted of 6 items which came from various subscales of POMS and represented "uncertainty and helplessness," which may be somewhat different to depression or sadness proper. Conclusion: The validity and reliability of K-POMS could be confirmed. The significant difference in K-POMS scores between depressive subjects and normal subjects suggests that K-POMS can be used clinically for the evaluation and screening of depression. The main structure of K-POMS is very similar to that of POMS, except the Confusion-Bewilderment factor which shows weak factor consistency in K-POMS. This may reflect some emotional characteristic of Koreans such as an undifferentiated aspect of cognitive efficiency. The sixth factor newly extracted from K-POMS also may be indicative of an unique emotional aspect of young Koreans.

• Journal of Intelligence and Information Systems
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• v.17 no.2
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• pp.61-75
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• 2011

A Geographic Information System(GIS) is a system that captures, stores, analyzes, manages and presents data with reference to geographic location data. In the later 1990s and earlier 2000s it was limitedly used in government sectors such as public utility management, urban planning, landscape architecture, and environmental contamination control. However, a growing number of open-source packages running on a range of operating systems enabled many private enterprises to explore the concept of viewing GIS-based sales and customer data over their own computer monitors. K telecommunication company has dominated the Korean telecommunication market by providing diverse services, such as high-speed internet, PSTN(Public Switched Telephone Network), VOLP (Voice Over Internet Protocol), and IPTV(Internet Protocol Television). Even though the telecommunication market in Korea is huge, the competition between major services providers is growing more fierce than ever before. Service providers struggled to acquire as many new customers as possible, attempted to cross sell more products to their regular customers, and made more efforts on retaining the best customers by offering unprecedented benefits. Most service providers including K telecommunication company tried to adopt the concept of customer relationship management(CRM), and analyze customer's demographic and transactional data statistically in order to understand their customer's behavior. However, managing customer information has still remained at the basic level, and the quality and the quantity of customer data were not enough not only to understand the customers but also to design a strategy for marketing and sales. For example, the currently used 3,074 legal regional divisions, which are originally defined by the government, were too broad to calculate sub-regional customer's service subscription and cancellation ratio. Additional external data such as house size, house price, and household demographics are also needed to measure sales potential. Furthermore, making tables and reports were time consuming and they were insufficient to make a clear judgment about the market situation. In 2009, this company needed a dramatic shift in the way marketing and sales activities, and finally developed a dedicated GIS_based market analysis and sales management system. This system made huge improvement in the efficiency with which the company was able to manage and organize all customer and sales related information, and access to those information easily and visually. After the GIS information system was developed, and applied to marketing and sales activities at the corporate level, the company was reported to increase sales and market share substantially. This was due to the fact that by analyzing past market and sales initiatives, creating sales potential, and targeting key markets, the system could make suggestions and enable the company to focus its resources on the demographics most likely to respond to the promotion. This paper reviews subjective and unclear marketing and sales activities that K telecommunication company operated, and introduces the whole process of developing the GIS information system. The process consists of the following 5 modules : (1) Customer profile cleansing and standardization, (2) Internal/External DB enrichment, (3) Segmentation of 3,074 legal regions into 46,590 sub_regions called blocks, (4) GIS data mart design, and (5) GIS system construction. The objective of this case study is to emphasize the need of GIS system and how it works in the private enterprises by reviewing the development process of the K company's market analysis and sales management system. We hope that this paper suggest valuable guideline to companies that consider introducing or constructing a GIS information system.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.434-442
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• 2015

The process of cultivation and production of oak mushroom (Lentinula edodes (Berk.) Pegler) on sawdust surface beds were investigated. Sawdust surface bed cultivation is the method by which oak mushrooms are cultured and produced on sterilized sawdust surface bed without using bags. The bed was made by inoculating with 3 to 1 ratio of bed sawdust to oak mushroom mycelial inoculum. The sawdust bed medium with 65% water content was pasteurized at $65^{\circ}C$, inoculated with sawdust spawn and spread on the surface on vinyl film in cultivation shed. During 78 days of cultivation period, water content in the medium varied from 61 to 72%, its pH decreased from 5.6 to 3.9~4.6 and ergosterol concentration increased to $0.33{\sim}0.59{\mu}g/g$. $CO_2$ concentration in the medium rapidly increased to 8.06% in two weeks. In seven weeks the medium surface started browning and $CO_2$ concentration increased to about 5.63%. Until 11th week the $CO_2$ concentration was maintained at 6~7%. After removing the plastic cover on the bed for ventilation in 12 weeks, $CO_2$ within the bed reduced dramatically to 1.5%. In the cultivation shed the internal temperature was $7.1{\sim}29^{\circ}C$ and humidity was 27.3 to 100%, while bed temperature ranged $11.6{\sim}30^{\circ}C$. Oak mushroom fruiting started from late July, in 120 days after bed establishment in late March and continued for approximately 100 days until early December with eight cycles of irrigation treatment. The mushroom yield of the eight cycles were 288~352 kg during the 1st (7/29~8/4) to 3rd cycle (9/3~9/7), 800 kg at the 4th cycle (9/19~9/24), 1,296~1,853 kg during 5th (10/3~10/8) to 7th cycle (4.11~11/9) and 990 kg at 8th cycle (11/23~12/7). Total production was approximately 7.4 tons from 33.0 tons of oak sawdust medium, thus harvest efficiency of the mushroom production was approximately 22.4%.

• The Journal of the Korea Contents Association
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• v.16 no.1
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• pp.24-41
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• 2016

Study is about Bit Coin that is electronic cash that is received attention globally in recent. It is increasing domestically that uses bit coin for convenience of micro payment, and also bit coin is possible to exchange each countries' currency. In this point, we searched understanding degree and acceptance of bit coin. Also we applied transformed TAM(Technology Acceptance Model) to search factors that have an effect on consumers' intention to use it. In advance, we analyze features of bit coin, and extract factors through preceding researches for existing electronic cash, because studies for intention to use bit coin are weak in internal and external. First of results is that 'economic efficiency' which is a characteristic variable of bit coin influences 'intention to use,' a dependent variable through 'perceived usefulness,' a parameter. It was investigated that monetary and mental costs that was costed when we use bit coin were less than using other cash. Secondly, 'payment convenience' that is a characteristic variable affects 'intention to use', a dependent variable through 'perceived usefulness,' a parameter. It was measured that problems of inconvenience that include transaction process, cash management time shortage and exchange changes will be solved by using bit coin. Thirdly, 'reliability' that is a perceived risk variable of bit coin has a direct effect on 'intention to use,' a dependent variable. It was investigated that we could achieve purpose of payment because we weren't influenced by breakdown on system by processing distributed database in some computers. Fourthly, 'perceived usefulness,' a parameter of bit coin directly affects 'intention to use,' a dependent variable. Then consumers who want to use bit coin are fascinated bit coin for various usability. Moreover, we want to provide implications to all of finance corporations, companies related electronic cash and bit coin users based on these results.

• Journal of radiological science and technology
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• v.29 no.4
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• pp.267-274
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• 2006

The evaluation of GB stones with ultrasound has proved to be useful procedure in patient with symptoms of cholelithiasis. GB is evaluated for size, wall thickness, presence of internal reflections within the lumen and posterior acoustic shadowing or enhancement in Ultrsonography. The patient position should be shifted during procedure to demonstrate further the presence of stone within the GB. Patient scanned at the Rt. subcostal region in supine, right lateral, Lt. down decubitus, and upright sitting position. So GB stone should shift to dependent area of GB. Often, GB is not markedly distended in the presence of cholethiasis, and so the diagnosis becomes more difficult. One of the more difficult areas for detection of a GB stones are embeded in the cystic duct region. And since the GB is adjacent to the duodenum and hepatic flexure, its may be difficult to visualizing a GB stone. When patient study position changes frome supine to other position, stones displaced the site. But if its are polyps, not changes the site whatever patient positions. It is very important to what make different GB stones or polyps. We have studied about mobility of GB stones according to the patients position(supine, Lt. down decubitus, $30^{\circ} LAO. sitting and hand-knee). So we have a result, stones wherever localized within the GB, changed 100% its position in the hand-knee position and the others appeared at least 90%. In this study, when a large stones are located through fundus-body and body-neck, does not changing the stones position in spite of varied patient's positions. But hand-knee positions can identified GB stones, because its make changed the position of stons from posterior wall to anterior wall within the GB. We recommend the hand-knee position for differentiation GB stones from polyps.

• Journal of Nutrition and Health
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• v.41 no.2
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• pp.147-155
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• 2008

Medical nutrition therapy (MNT) is considered a keystone of medical treatment of chronic diseases. However, only few studies have evaluated medical and economical outcome of MNT. The study was performed on the patient with type 2 diabetes mellitus to evaluate the effect of clinical and cost-effective outcomes of MNT. Subjects from two general hospitals were randomly assigned to two different groups; One receiving basic nutritional education (BE) (n = 35), and the other receiving intensive nutritional education (IE) (n = 32) for a 6-month clinical trial. The group which received BE had a single visit with a dietitian, while the other group which received IE had an initial visit with a dietitian addition to two visits during the first 4 weeks of the study periods. Anthropometric parameters, blood components, and dietary intake were measures at the beginning of study period and after 6 month. Cost-effective analysis included direct labor costs, educational materials and medication cost difference during 6 months. After 6 month, subjects from IE group showed significant reduction of body weight (p <0.05) and systolic blood pressure (p <0.05), whereas BE group did not show any significant changes. Result from biochemical indices showed glycated hemoglobin concentration was significantly reduced by 0.7% (p <0.05) only in the IE group. The ratio of energy intake to prescribed energy intake decreased significantly in both groups (p <0.05). Mean time taken for a dietitian to educate the subject was 67.9 ${\pm}$ 9.3 min/person for BE group, while 96.4 ${\pm}$ 12.2 min/person for IE group. Mean number of educational materials was 1.9 ${\pm}$ 0.7/person for BE group and 2.5 ${\pm}$ 0.7/person for IE group. Change in glycated hemoglobin level along the 6 month period of study can be achieved with an investment of \88,510/% by implementing BE and \53,691/% by implementing IE. Considering the net cost-effect of blood glucose control and HbA Ic, IE which provides MNT by dietitian had a cost efficiency advantage than that of BE. According to this study, MNT provided by dietitian had a significant improvements in medical and clinical outcomes compared to that of BE intervention. Therefore, MNT protocol should be performed by systemic intensive nutrition care by dietitian in clinical setting to achieve good therapeutic results of DM with lower cost.

• KDI Journal of Economic Policy
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• v.32 no.2
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• pp.55-92
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• 2010

In terms of labor market accomplishments, such as income, size of the company, and the matching quality between one's job and college major (specialization), a very large discrepancy is observed between the graduates from colleges located in Seoul and those outside Seoul. But, when the department average score of the Scholastic Aptitude Test (SAT) at the time of college entrance is controlled for, the discrepancy is found to be reduced to a considerable degree. In the case of wage gap, at least two third can be explained by the SAT score gap. The remaining wage gap seems to reflect the characteristics of workplace. In other words, graduates with high SAT scores enter colleges located in Seoul and thus tend to find better jobs leading to earning differences. This result that confirms the importance of aptitude test scores suggests that in the labor market, one of the major reasons behind a lower accomplishment of the graduate from local colleges is due to a lower competitiveness of local colleges in attracting the brightest students. But, this should not be viewed as only an internal problem of local colleges. This is because the growth of local economies tends to haul the advancement of local colleges in that area rather than being the other way around. The agglomeration effect in Seoul where headquarters of large corporations and financial institutions gather is the factor that has elevated the status of colleges located in Seoul since this provides highly preferred job choices of graduates. When the competitiveness of college is significantly influenced by exogenous factors, such as the vicinity to Seoul, the effort being made by colleges alone would not be enough to improve the situation. However, the central government, too, is not in the position to carry out countermeasure policies for such problems. The regional development strategy boosted through supportive policies for local colleges, such as financial support, is not based on the persuasive and empirical grounds. It is true that college education is universal and that the government''s intervention in assisting local colleges to secure basic conditions, such as tenure faculty and adequate facilities is necessary. However, the way of intervention should not be a support-only type. In order to improve the efficiency and effect of financial support, restructuring programs, including the merger and integration of insolvent colleges, should be underway prior to providing support. In addition, when the policy is focused on education recipients-local college students, and not on education providers-local colleges, the importance of regional gap in compulsory education (elementary and junior high schools) turns out to be much important as the gap between metropolitan area colleges and local colleges. Considering the educational gap before college entrance shown from the discrepancies of aptitude test scores among different regions, the imbalance between regions in terms of human resources is apparently derived from compulsory education, and not from college education. Therefore, there is a need to double the policy efforts to reduce the educational gap among different regions. In addition, given the current situation where it is difficult to find appropriate ex post facto policy measures to solve the problem of income gap between the graduates from metropolitan colleges and local colleges, it can be said that improving the environment for compulsory education in local areas is a growing necessity for bridging the educational gap among different regions.

• Clean Technology
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• v.26 no.2
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• pp.102-108
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• 2020

In recent years, packed column has been widely used in separation processes, such as absorption, desorption, distillation, and extraction, in the petrochemical, fine chemistry, and environmental industries. Packed column is used as a contacting facility for gas-liquid and liquid-liquid systems filled with random packed materials in the column. Packed column has various advantages such as low pressure drop, economical efficiency, thermally sensitive liquids, easy repairing restoration, and noxious gas treatment. The performance of a packed column is highly dependent on the maintenance of good gas and liquid distribution throughout a packed bed; thus, this is an important consideration in a design of packed column. In this study, hydraulic pressure drop, hold-up as a function of liquid load, and mass transfer in the air, air/water, and air-NH₃/water systems were studied to find the geometrical characteristic for raschig super-ring experiment dry pressure drop. Based on the results, design factors and operating conditions to handle noxious gases were obtained. The dry pressure drop of the random packing raschig super-ring was linearly increased as a function of gas capacity factor with various liquid loads in the Air/Water system. This result is lower than that of 35 mm Pall-ring, which is most commonly used in the industrial field. Also, it can be found that the hydraulic pressure drop of raschig super-ring is consistently increased by gas capacity factor with various liquid loads. When gas capacity factor with various liquid loads is increased from 1.855 to 2.323 kg^-1/2 m^-1/2 S^-1, hydraulic pressure drop increases around 17%. Finally, the liquid hold-up related to packing volume, which is a parameter of specific liquid load depending on gas capacity factor, shows consistent increase by around 3.84 kg^-1/2 m^-1/2 S^-1 of the gas capacity factor. However, liquid hold-up significantly increases above it.